The teenagers were convicted of posting pictures with lewd remarks on the photo-sharing app Instagram.

Two Swedish teenage girls were found guilty of defamation Tuesday for posting sexual insults about other youngsters on the photo sharing app Instagram.

The court convicted the girls, aged 15 and 16, for writing explicit, derogatory remarks next to pictures of 38 young people, mostly girls, via an anonymous account on Instagram.

Posted in December, the comments quickly spread on the Internet before the account was shut down, and caused hundreds of young people to take to the streets in Gothenburg, the teenagers' hometown, in protests that turned violent.

Cyberbullying among young people has become an increasing concern with the growth of social media, and a lawyer in the Swedish case said the convictions showed that people who post defamatory comments, believing they are anonymous, can still be vulnerable to prosecution.

"Many think they are anonymous when they are sitting behind a computer and therefore take greater liberties than if that anonymity wasn't there," the plaintiffs' attorney, Arash Raoufi, said.

"The verdict sends a signal to young people and society that this indignity culture cannot be allowed to exist. I hope it will also result in parents being more alert to what kids do at the computer," he said.

In the Gothenburg case, the plaintiffs provided screenshots of the derogatory remarks while forensic evidence tied the teenagers to the account.

The teenagers, one of whom had confessed to being behind the account while the other denied involvement, were both fined and one was also sentenced to community service.

Instagram, bought by Facebook last year for $715 million, was launched in 2010 and said in March that it had 10 million users.